The present invention relates to a workability evaluating apparatus, a workability evaluating method, and a workability evaluating program, each of which makes quantitative evaluations of workability, such as the smoothness or comfortability of operating equipment, based on myoelectric potentials.
A human being or an animal bends or stretches limbs or the like by contracting a muscle to thereby perform a desired action. In performing an action, a given muscle contracts and another muscle corresponding thereto relaxes. In other words, a human being or an animal performs an action by antagonizing muscles. The muscle which contracts during an action is termed a prime mover (agonist), while a muscle which relaxes is termed an antagonist.
In the case of steering a steering wheel of a vehicle during driving or operating a control lever of an aircraft during flight, symmetric contraction is caused between the prime mover and the antagonist when an excessive strain results from mental load or a difficult control operation.
As means for instantaneously reflecting such muscle activity, an electromyogram representing a myoelectric potential as time-series data has been used. The electromyogram has been used as optimum bio-information for capturing instantaneous sensory information.
There has been proposed a technology with which load placed on a driver due to a driving operation is determined by using an electromyogram and the result of the determination is used for a vehicle control apparatus for properly setting control conditions for a vehicle (see, e.g., JP 2002-225585 A).
JP 2002-225585 A discloses a process of measuring both of a myoelectric potential at a prime mover and a myoelectric potential at an antagonist, calculating a value (competitive characteristic quantity) associated with the competition between the two myoelectric potentials, and determining the magnitude of a load placed on a driver due to a driving operation, based on the competitive characteristic quantity.
More specifically, the myoelectric potentials at the competitive muscles of the driver are measured by using myoelectric potential sensors, and the competitive characteristic quantity is calculated from the competitive value between the measured myoelectric potentials. When the calculated competitive characteristic quantity exceeds a predetermined threshold, it is determined that the load placed on the driver due to the driving operation has increased (paragraphs [0005] and [0006] in JP 2002-225585 A).
In JP 2002-225585 A, the measurement of the myoelectric potentials is performed by attaching the electrodes of the myoelectric potential sensors (detection sensors) to the surface of the skin. It has been known that, however, when myoelectric potential sensors are attached again after being peeled off, the resistance values between the surface of the skin and the electrodes vary, and therefore it is difficult to maintain the levels of the myoelectric potentials. That is, when the voltage value of the myoelectric potentials is used as an index representing muscle activity in an absolute sense, a determination error may occur occasionally.